High density planar electrical interface

ABSTRACT

An apparatus including a substrate having a plurality of through holes and a plurality of cables, including wires and/or coaxial cables, extending through respective ones of the plurality of through holes of the substrate. Each of the cables comprises a conductor and terminates about a surface of the substrate such that the conductors of respective ones of plurality of cables are planarly aligned and available for electrical contact. A system including a cable interface extending through respective ones of a plurality of through holes of a body of the interface; an interconnection component comprising a first plurality of contact points aligned with respective ones of conductors of the plurality of cables and a second plurality of contact points aligned to corresponding contact points of a device to be tested. Also, a method of routing signals through the conductors of the plurality of cables between electronic components.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.09/886,521, filed Jun. 20, 2001 U.S. Pat. No. 7,108,546.

BACKGROUND

1. Field

The invention relates to coupling electronic components and, in oneaspect, to techniques for performing test and burn-in procedures onintegrated circuit devices prior to their packaging, preferably prior tothe individual devices being singulated from a wafer.

2. Background

Individual integrated circuit devices (dies) are typically produced bycreating several identical devices on a semiconductor wafer, using knowntechniques of photolithography, deposition, and the like. Generally,these processes are intended to create a plurality of fully-functionalintegrated circuit devices prior to singulating (severing) theindividual dies from the wafer. In practice, however, certain defects inthe processing of the wafer inevitably lead to some of the dies being“good” (fully-functional) and some of the dies being “bad”(partially-functional or non-functional). It is generally desirable tobe able to identify which of the plurality of dies on a wafer are gooddies prior to their packaging, and preferably prior to their beingsingulated from the wafer. To this end, a device or a wafer “tester” or“prober” may advantageously be employed to make a plurality of discretepressure connections to a like plurality of discrete connection pads(bond pads) on the dies. In this manner, the dies can be tested andexercised prior to packaging, and preferably, prior to singulating thedies from the wafer.

A die or a plurality of dies on a wafer may be tested using an automatedtest system. Such a test system usually includes a processor thatexecutes a test program engineered for testing devices (dies) under test(“DUTs”). A “probe card assembly” receives the test data from theprocessor and delivers it to locations in the DUTs. Typically, aplurality of probe elements are connected to the probe card assembly toeffect pressure connections to respective bond pads of DUTs toeffectuate the testing.

One type of probe card assembly includes a probe card. Probe cards aretypically conventional circuit board substrates (e.g., ofepoxy-impregnated fiberglass material) formed as circular rings, withhundreds of probe elements (needles) bonded to, and extending from aninner periphery of, the ring. Circuit modules and conductive traces(lines) of preferably equal lengths, are associated with each of theprobe elements.

A second representative type of probe card assembly is described incommonly-owned, U.S. Pat. No. 5,974,662 issued Nov. 2, 1999, titled“Method of Planarizing Tips of Probe Elements of a Probe Card Assembly,”and U.S. Pat. No. 6,050,829 issued on Apr. 18, 2000, titled “MakingDiscrete Power Connections to a Space Transformer of a Probe CardAssembly,” each incorporated herein by reference. In one embodiment, theprobe card assembly includes as its major functional components a probecard, an interposer, and a space transformer. The probe card is acircuit board substrate having terminals arranged about an innerperiphery at a suitable pitch such as a 100 mil pitch.

To reduce the contact pitch of the probe card to a pitch of a DUT, aspace transformer may be utilized. A typical space transformer, forexample as described in U.S. Pat. No. 6,050,829, includes a suitablecircuitized substrate, such as a multi-layer ceramic substrate having aplurality of terminals disposed on opposites sides thereof.Interconnection elements, such as resilient interconnection elementsdescribed in the referenced, commonly-owned documents are used to couplethe space transformer to the probe card and to a DUT. To couple to theprobe card, the contact pads and/or interconnection elements aredisposed at the pitch of the corresponding pads of the probe card (e.g.,100 mils), and the plurality of contact pads and/or interconnectionelements to be coupled to a DUT may be disposed at a finer (closer)pitch of, for example, 50 mils, with ends of the interconnectionelements coupling to contacts of the DUT at possibly an even finer pitch(e.g., a 10 mil pitch).

Between the space transformer and the probe card, an interposer may beemployed to provide dimensional stability to the probe card assembly andadjust the planarity of the assembly in a Z-dimension to improve theelectrical contact between the assembly and DUTs. One interposer is, forexample, and as described in U.S. Pat. No. 5,974,662, a dielectricsubstrate having interconnection elements, including any of theresilient interconnection elements noted above, mounted to and extendingfrom opposite sides of the substrate. The pitch of the interconnectionelements is selected to correspond to the pitch of the probe cardcontact pads and the space transformer contact pads, respectively.

As described above, a typical probe card has hundreds or thousands ofprobe elements or terminals about an inner periphery and wired toconductive traces through the probe card to terminals. Such terminalsmay be disposed along an outer periphery of the probe card ring.Typically, conductive probe pins, such as “pogo pins,” electricallyconnect these terminals to host equipment such as a processor thatexecutes a test program through a test head and associated circuitry.

One concern to designers of probe card assemblies is that to get fromthe pin electronics of the host equipment to the probe tips on the probecard, the signals must travel through a multi-element signal path (e.g.,pogo pins, terminals, traces, etc.). These various elements havephysical and electrical performance limitations that adversely affectconventional tester technology. For example, the pogo pins and theirterminal coupling have certain known performance limitations which areaddressed by matching pad capacitance and impedance to some arbitraryvalues. The probe card board material represents a further performancelimitation in that the loss tangent of typical FR4 fiberglass materialis such that even a few inches of this material in the signal path canrepresent significant attenuation and signal distortion.

Controlling impedance characteristics (capacitance, inductance, andcontact resistance) and minimizing cross-talk between a multiplicity ofsignals, typically several hundreds, from the tester pin electronics tothe device under test microcircuit represents a significant technicalchallenge. What is needed is improved tester technology that reduces theperformance limitations of the conventional tester technology.

SUMMARY

An apparatus is disclosed. In one embodiment, the apparatus includes asubstrate having a plurality of through holes and a plurality of cables,including wires and/or coaxial cables, extending through respective onesof the plurality of through holes of the substrate. Each of the cablescomprises a conductor and terminates about a surface of the substratesuch that the conductors of respective ones of plurality of cables areplanarly aligned and available for electrical contact. The plurality ofthrough holes of a substrate may be configured such that the conductorsare aligned with respect to contact points of an electronic component,including an integrated circuit device, a device package, a socket, or acircuit test component such as an interposer or space transformer of anintegrated circuit test assembly. In terms of testing systems, theapparatus may serve as an interface between a DUT and host testequipment, eliminating a probe card and pogo pins and their associatedperformance limitations.

A system is also disclosed. In one embodiment, the system comprises acable interface comprising a plurality of cables, including wires and/orcoaxial cables, extending through respective ones of a plurality ofthrough holes of a body of the interface; an interconnection componentcomprising a first plurality of contact points aligned with respectiveones of conductors of the plurality of cables and a second plurality ofcontact points aligned to corresponding contact points of a device to betested. The system further includes a testing component coupled to asecond end of the plurality of coaxial cables and comprising circuitryto test a device.

A method is further disclosed. In one embodiment, the method includesassembling a plurality of cables, including wires and/or coaxial cables,in an array suitable for accessing contact points of a device to betested with respective conductors of the plurality of the cables, androuting signals through the conductors of the plurality of cablesbetween a testing component and a device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic, cross-sectional side view of one embodiment ofa cable interface.

FIG. 2 shows a schematic, top perspective exploded view of a portion ofthe cable interface of FIG. 1.

FIG. 3 shows a schematic, top perspective view of a portion of the cableinterface of FIG. 1 with cables fitted in through holes through a firstsubstrate body.

FIG. 4 shows a schematic side view of the cable interface of FIG. 1after introducing a material to form a second substrate body over endsof the cables extending through the first substrate body.

FIG. 5 shows a schematic, top perspective view of the structure of FIG.4 after lapping or planarizing the second substrate body to exposeconductors of the cables.

FIG. 6 shows a schematic, top perspective view of a plurality of cableinterface sub-assemblies arranged in an array.

FIG. 7 shows a schematic, top perspective view of a single exposed cableend through a cable interface body having a coating introduced onconductors of the cable.

FIG. 8 shows a schematic, top perspective view of a single exposed cableend through a cable interface body in a first embodiment where contactpads are coupled to conductors of the cable and planarly arranged on thesurface of the interface body.

FIG. 9 shows a schematic, top perspective view of a single exposed cableend through a cable interface body in a second embodiment where contactpads are coupled to conductors of the cable and planarly arranged on thesurface of the interface body.

FIG. 10 shows a schematic, exploded, cross-sectional view of oneembodiment of a testing system.

FIG. 11 shows a schematic perspective and partial cross-sectional viewof a single coaxial cable of a cable interface suitable for use in thetesting system of FIG. 10.

FIG. 12 shows a schematic cross-sectional side view of a secondembodiment of a testing system.

FIG. 13 shows a schematic cross-sectional side view of a thirdembodiment of a testing system.

FIG. 14 shows a schematic cross-sectional side view of a fourthembodiment of a testing system.

FIG. 15 shows a schematic top view of the portion of the testing systemof FIG. 14.

FIG. 16 shows a schematic cross-sectional side view of a fifthembodiment of a testing system.

DETAILED DESCRIPTION

An apparatus suitable as an interface between electronic components; atesting system; and a method of routing signals between a tester and anelectronic component are described. In terms of integrated circuitdevice testing, including wafer or device-level testing, the apparatus,system and method, offer an improvement over prior art technologies byeliminating, in one regard, a probe card and its assorted components(e.g., pogo pins, terminals, tracing, etc.). In this manner, the variousembodiments described address the performance limitations of probe cardsand their assorted components regarding DUT tester technology.

FIG. 1 shows a schematic cross-sectional view of an embodiment of acable interface. Cable interface 120 includes a plurality of cables 125A. . . 125N extending therethrough. As described herein, cables 125A . .. 125N include conductive wires, such as solid or stranded copper wires,and cables, such as coaxial cables or a mixture of conductive wires andcoaxial cables. Cables 125A . . . 125N are potted in second substratebody 230 so that conductive ends (conductors) of cables 125A . . . 125Nare exposed and planarly aligned.

In one embodiment, cable interface 120 is configured to function as anelectrical interface between contacts or interconnections of twoelectronic components. Cables 125A . . . 125N may act as signal linesbetween two devices and/or supply and return lines between electroniccomponents. Exposed conductors of cables 125A . . . 125N through secondsubstrate body 230 (and about a surface of cable interface 120) are afirst plurality of contact points of cable interface 120 with anelectronic component. Suitable electronic components for contacting withexposed conductors of cables 125A . . . 125N include, but are notlimited to, an integrated circuit device, a device package, a socket,and components of a testing system, such as a space transformer and/oran interposer. It is appreciated that the number and pitch ofcorresponding contact points of the electronic component will dictate,in part, the number and pitch of cables 125A . . . 125N disposed incable interface 120. Referring to FIG. 1, cables 125A . . . 125N arefixedly arranged within first substrate body 225 according to an arraysuitable for, in one instance, an electrical component to which suchcables will contact.

The exposed conductors about the surface of cable interface 120 act ascontact points for coupling to an electronic component. Such contactpoints may be engaged by, for example, interconnection elements. Suchinterconnections may make temporary pressure connections with theconductors of cable interface 120 or make more permanent connectionthrough bonding of the interconnection elements to the conductors. Inthe latter example, cable interface 120 may form part of a device socketfor coupling to an electronic component, with, for example, a sockethousing coupled to the body of cable interface 120.

Suitable interconnection elements for coupling to contact points(conductors) of cable interface 120 include, but are not limited to,interconnection elements described in the following conmonly-ownedapplications and patents incorporated herein by reference:

1) U.S. Pat. No. 5,974,662 issued Nov. 2, 1999, titled “Method ofPlanarizing Tips of Probe Elements of a Probe Card Assembly”;

2) U.S. Pat. No. 5,476,211 issued Dec. 19, 1995, titled “Method ofManufacturing Electrical Contacts Using a Sacrificial Member”;

3) U.S. patent application Ser. No. 09/397,779, filed Sep. 16, 1999,titled “Electronic Assembly Comprising a Substrate and a Plurality ofSpringable Interconnection Elements Secured to Terminals of theSubstrate”;

4) U.S. patent application Ser. No. 09/245,499, filed Feb. 5, 1999,titled “Method of Manufacturing Raised Electrical Contact Pattern ofControlled Geometry”;

5) U.S. patent application Ser. No. 08/802,054, filed Feb. 18, 1997,titled “Microelectronic Contact Structure, and Method of Making Same”;

6) U.S. patent application Ser. No. 09/473,414, filed Dec. 28, 1999,titled “Interconnect for Microelectronic Structures with Enhanced SpringCharacteristics”;

7) U.S. patent application Ser. No. 09/547,561, filed Apr. 12, 2000,titled “Shaped Spring”;

8) U.S. patent application Ser. No. 09/547,560, filed Apr. 12, 2000,titled “Methods of Fabricating and Using Shaped Springs”.

Referring to FIG. 2, a second plurality of contact points of cables 125A. . . 125N of cable interface 120 are at second ends of cables and mayeach have conventional connectors, such as British Naval Connectors(BNCs) for coaxial cables, suitable for coupling to an electroniccomponent such as a processor. Alternatively, the second plurality ofcontact points may be assembled in a second interface or interfaces,such as one or more sockets, for connection to a second electroniccomponent. These ends may also be connected to a second component of thetype shown in FIG. 1 (i.e., a second cable interface).

FIG. 2 shows an exploded view of a portion of cable interface 120. Inthis example, cable interface 120 includes first substrate body 225 thatis a solid substrate of, for example, a fiberglass, ceramic, polymer, orconductive material. In one embodiment, first substrate body 225 has athickness suitable for maintaining the rigidity of cable interface 120.In use in integrated circuit device testing, issues such as theplanarity of the first contact points are significant and therefore thebody of cable interface 120 should be able to demonstrate a suitablestiffness or rigidity for such use. A thickness on the order of a fewhundred mils of a fiberglass, ceramic, or certain polymer materials ormetals will suffice for most device testing operations.

In the illustrated embodiment, first substrate body 225 is approximatelyrectangular or square having XY dimensions similar to an interposer orspace transformer to which it may be, in one embodiment, coupled.Alternatively, first substrate body 225 may be circular or of anothershape as the dimensions of the application may dictate. The dimensionsare also selected to be suitable to house the desired number of cables125A . . . 125N for the interfacing operation given the outside diameterof the selected cable. In use as a component of an integrated circuittesting device, for example, it may be desired to have 1,000 contactpoints for a logic tester and 3,000 contact points for a memory tester.Suitably sized single-conductor cables having outside diameters on theorder of 62.5 mils (1.5 mm) to 31.2 mils (0.75 mm) may be accommodatedon a square substrate of 3 inches by 3 inches (7.6 cm by 7.6 cm) andprovide a sufficient number of conductors to accommodate those contactpoints. Alternatively, a large array may be assembled fromsub-assemblies, each with a smaller number of cables that are fittedtogether (e.g., mechanically coupled) to form a large array.

As shown in FIG. 2, first substrate body 225 has a plurality ofZ-direction through holes 128 formed therethrough. Through holes 128locate cables 125A . . . 125N in an X-Y plane according to the desiredcontact alignment for the interface structure. In one embodiment,through holes 128 are machine-drilled through the solid substratematerial of first substrate body 225 to the desired alignment. Throughholes 128 are sized to accommodate cables 125A . . . 125N such thatcables 125A . . . 125N extend through first substrate body 225.

FIG. 3 shows the structure of FIG. 2 after the insertion of cables 125A. . . 125N through through holes 128 in first substrate body 225. Inthis embodiment, cables 125A . . . 125N are fitted in such a way thattheir end portions extend beyond superior surface 226 of first substratebody 225.

Following the introduction of cables 125A . . . 125N through throughholes 128 and above superior surface 226 of first substrate body 225,first substrate body 225 and fitted cables 125A . . . 125N are potted oroverfilled with, in one embodiment, a suitable dielectric material, assecond substrate body 230 as shown in FIG. 4. In one embodiment, secondsubstrate body 230 is selected such that it may be introduced by flowingover superior surface 226 of first substrate body 225 and then cured toform a solid structure, such as by thermal or radiation curing means asknown in the art. Polymers such as certain polyimides or epoxies aresuitable for such potting. A thickness of second substrate body 230, inone embodiment, is determined by that amount necessary to encapsulate oroverfill (in a Z-direction) protruding ends of cables 125A . . . 125N.

Following the introduction and curing of second substrate body 230 overfirst substrate body 225, the structure is planarized or lapped in an XYplane in such a manner to expose ends of previously encapsulated cables125A . . . 1125N. Suitable planarization techniques include, but are notlimited to, etching or chemical and/or mechanical polishing as known inthe art.

FIG. 5 shows cable interface 120 following the planarization or lappingof second substrate body 230 to expose ends of cables 125A . . . 125Nconductors of cables 125A . . . 125N such that conductors are availablefor contact according to a pre-selected orientation. In the case ofcables of wires, such as copper wires, the wire itself is the conductor.In the case of coaxial cables, such cables typically include twoconductors with a solid central conductor surrounded by an insulator,which is in turn surrounded by a cylindrical shield woven from finewires. In such case, after planarization or lapping, both the centralconductor and the shield are available for electrical contact. It isappreciated that any jacketing on the cable, for example, surroundingthe shield of a coaxial cable, is removed at the ends during theplanarization or lapping to expose the shield.

FIG. 5 shows cables 125A . . . 125N disposed at a predetermined pitchfor contact between the cable ends of cable interface 120 and electroniccomponent. In FIG. 5, the X-direction pitch is represented by referencenumeral 150 and a Y-direction pitch by reference numeral 155. A suitablepitch for coupling to current state of art electronic components throughthe use of interconnection elements, is on the order of 50 mils (1.3 mm)to 100 mils (2.5 mm). The use of the interconnection elements mentioned,however, would allow even finer pitches to be used (e.g., <200 μm). InFIG. 5, X-direction pitch 150 and the Y-direction pitch 155 is definedbetween the center of adjacent conductors.

FIG. 6 shows an example of a plurality of cable interfaces assub-assemblies coupled together to form a single array. Such an array ofsub-assemblies can be used to accommodate a large number of contactpoints to which the sub-assemblies interface. Referring to FIG. 6, cableinterfaces 120A, 120B, 120C, 120D, and 120E are mechanically coupledtogether in a large array. One type of mechanical coupling isforce-fitting male and female components of respective cable-interfacesub-assemblies together. FIG. 6 shows cable interface 120C having femaleconnector 122C (in this example, a slot formed in first substrate body225C). A male connector, such as male connector 123F of cable interface120F is sized to fit (mate) with female connector 122C in apressure-fit, decoupable relationship. Cable interface 120F alsoincludes one or more female connectors, such as female connectors 122Fand 124F.

It is appreciated that the cable interfaces of an array such as shown inFIG. 6 may be configured of various dimensions (e.g., they may all be ofsimilar rectangular dimensions or different rectangular dimensions orother geometric configurations). The cable interfaces of an array mayalso be of similar or varying thickness. Finally, when assembled in anarray, the cables of individual cable interfaces may be used fordifferent purposes. For example, the cables of cable interface 120A mayfunction as signal lines for a particular application while the cablesof cable interface 120B may function as supply (power) or return(ground) lines for the same application.

FIG. 7 shows an isolated close-up view of an end of cable 125A exposedafter planarization or lapping through second substrate body 230. Inthis top perspective view, a portion of second substrate body 230 is cutaway, exposing cable 125A below surface 232 of second substrate body230. In this embodiment, cable 125A is a coaxial cable comprising solidcentral conductor 160 of, for example, a copper material. Centralconductor 160 is surrounded by insulator or dielectric material 165 of,for example, polyethylene or TEFLON®. Surrounding insulator ordielectric material 165 is shield 170 of, for example, woven copperwires. Coaxial cables are selected, in one embodiment, as a suitablesignal transmission line because of their generally constant-impedanceproperty. Another advantage of coaxial cables is that shield 170 may beused as a supply/return line for central conductor 160, such as a lineto ground.

As noted above, in one embodiment, central conductor 160 and shield 170may serve as contact points for contact with an electronic component.Alternatively, and in the embodiment shown, central conductor 160 andshield 170 are coated on the exposed surface by a conductive material.In one embodiment, the conductive material selected as a coating forcentral conductor 160 and shield 170 is a durable, inert material thatresists oxidation. A suitable material is, for example, gold (Au). Inthe case of gold, the conductive material may be coated over centralconductor 160 and shield 170 by an electroplating process. By way ofexample, an electroplating process involves introducing metallic ions,such as gold ions, in a pH neutral-base solution, and reducing the ionsto a metallic state by applying current between central conductor 160and/or shield 170 and an anode of an electroplating cell in the presenceof the solution. It should be appreciated that non-conductingelectroless plating deposition may also be used for coating.

FIG. 7 shows central conductor 160 having conductor material 180introduced thereon. Similarly, FIG. 7 shows shield 170 having conductormaterial 190 introduced thereon. In the case of an electroplatingprocess, the coating of conductor materials 180 and 190 (of similarmaterials) may be done simultaneously. In one embodiment, conductormaterials 180 and 190 have a thickness on the order of a few mils or asufficient amount to, in one embodiment, protect central conductor 160and shield 170 from oxidation. In one embodiment, the conductors areplanarly aligned about surface 232 of second substrate body 230 (i.e.,coated conductors may extend a few mils above the surface of secondsubstrate body 230).

In another embodiment, conductive pads may be coupled to centralconductor 160 and shield 170. FIG. 8 shows an embodiment where contactpoints or pads 162 and 172 are coupled to central conductor 160 andshield 170, respectively. In this manner, surface 232 of cable interface120 comprises a plurality of pads arranged at a corresponding pitch forcoupling to an electronic component. Contact points or pads 162 and 172,may be introduced as a conductive sheet (e.g., laminated to surface 232of second substrate body 230) and patterned into contact pads.Alternatively, the contact pads may be introduced by depositingconductive material as a blanket over surface 232 and patterning theconductive material into corresponding contact pads using, for example,lithographic techniques. Once patterned, the contact pads may beovercoated such as described above with a material that resistsoxidation such as gold. A dielectric material layer, such as a soldermasking material layer, may be introduced over surface 232 andsurrounding contact points or pads 162 and 172 so that only the contactpads are exposed on surface 232. In this perspective view, a portion ofsecond substrate body 230 is cut away, exposing cable 125A belowdielectric material layer 233 on surface 232 of second substrate body230.

FIG. 9 shows an embodiment where contact points or pads 163 and 173 arecoupled to central conductor 160 and shield 170, respectively, accordingto another configuration. In this embodiment, contact point or pad 163completely overlies central conductor 160 and contact point or pad 173overlies a portion of shield 170. The introduction (e.g., deposition)and patterning of contact points or pads 163 and 173 may be similar tothe introduction described above with reference to FIG. 8 and theaccompanying text. Also similar to the embodiment described withreference to FIG. 8, dielectric material layer 233 may be introducedover surface 232 around the contact points or pads.

FIG. 10 shows a representative application of cable interface 120. FIG.10 illustrates a test assembly according to one embodiment. Testassembly 300 includes as its major functional components, test processor310, cable interface 120, interposer 330, and space transformer 340. Inthis embodiment, test assembly 300 is suitable for use in makingtemporary interconnections or contacts to a wafer, such as wafer 400having integrated devices (dies) thereon. In this exploded,cross-sectional view, certain elements of various components are shownexaggerated for illustrative clarity. The vertical (as shown) alignmentof the various components is, however, properly indicated by the dashlines in the figure. The components referenced by bracket 10 aredescribed in conjunction with a probe card assembly detailed in U.S.Pat. No. 5,974,662 issued Nov. 2, 1999, titled “Method of PlanarizingTips of Probe Elements of a Probe Card Assembly, and its counterpartapplication, U.S. patent application Ser. No. 09/156,957, filed Sep. 18,1998, each incorporated herein by reference.

Referring to the component parts of test assembly 300, interposer 330includes, in this embodiment, substrate 335 having a plurality ofresilient interconnection elements 350 (two of many shown) mounted toand extending downward (as viewed) from the bottom surface of substrate335. Substrate 335 also includes a corresponding plurality ofinterconnection elements 360 (two of many) mounted to and extendingupward (as viewed) from the top surface of substrate 335.Interconnection elements 360 and 350 are, for example, resilientinterconnection elements of any of the spring shapes referenced in theaforementioned patent and application. Suitable alternativeinterconnection elements also include, but are not limited to, thoseinterconnection elements referenced above in connection with FIG. 1 andthe accompanying text.

Interposer 330 provides dimensional stability to test assembly 300 byadjusting the planarity of the assembly to improve the electricalcontact between the test assembly and wafer 400. Generally, the heightof the interconnection elements is dictated by the amount of compliancedesired. The interconnection elements may have a representative overallheight of about 20 to about 100 mils from respective bottom and topsurfaces of substrate 335. Typically, interconnection elements 350 andinterconnection elements 360 are at a pitch that matches a pitch of atypical prior art probe card, e.g., 100 mils.

In the assembly shown, the wiring interconnect layers in the probe cardare replaced by cable interface 120. Accordingly, cable interface 120includes a sufficient number of cables 125A . . . 125N (two of manyshown) with conductors disposed at a pitch selected, in one embodiment,to correspond with the pitch of interposer 330. Accordingly, ifinterposer 330 has 1000 interconnection elements disposed at a 100 milpitch (e.g., X- and Y-direction pitch of 100 mil) cable interface 120has a corresponding number of contact points (conductors) aligned in asimilar fashion with a similar 100 mil pitch. Such contact points may befor signals and supply (power) and return (ground) lines, either orboth. FIG. 11 shows a representative alignment of two interconnectionelements 350 to central conductor 160 and shield 170 of cable (e.g., acoaxial cable) 125A.

As shown in FIG. 10 and FIG. 11, interconnection elements 350 ofinterposer 330 make temporary pressure connections with conductors ofcable interface 120. One alternative to this configuration is to providecable interface 120 with relatively permanent interconnection elements(e.g., interconnection elements 350 bonded to conductors of cableinterface 120) having ends extending from the upper (as viewed) surfaceof cable interface 120 and making temporary pressure connections withcontact points (e.g., terminals) on interposer 330. Alternatively, theinterposer itself could be eliminated, and resilient contacts on eitherspace transformer 340 or cable interface 120 could interface directly topads on the other surface.

Referring to FIG. 10, space transformer 340 includes, in one embodiment,a suitable circuitized substrate 345, such as a multi-layer ceramicsubstrate, having a plurality of terminals 370 (two of many shown)disposed on the lower (as viewed) surface thereof and a plurality ofterminals 390 (two of many shown) disposed on the upper (as viewed)surface thereof. In this example, the lower plurality of terminals 370are disposed at the pitch of the tips of interconnection elements 360(e.g., 100 mils), and the upper plurality of terminals 390 are disposedat a finer (closer) pitch (e.g., 50 mils).

Plurality of interconnection elements 380 (two of many shown), e.g.,resilient interconnection elements referenced above, are mounted toterminals 390 of space transformer 340 and extend upward (as viewed)from the top surface of space transformer 340. As illustrated,interconnection elements 380 are suitably arranged so that their tips(distal ends) are spaced at an even finer pitch (e.g., 10 mils) thantheir bases (e.g., proximal ends) to contact, for example, contactpoints 410 (e.g., bond pads) on dies of wafer 400.

In use, interposer 330 is disposed on the top (as viewed) surface ofcable interface 120, and is within sufficient proximity so thatinterconnection elements 350 make a reliable pressure contact withcontact points of cable interface 120. Similarly, space transformer 140is stacked atop (as viewed) interposer 130 within sufficient proximityso that interconnection elements 360 make a reliable pressure contactwith terminals 370 at space transformer 140. Any suitable mechanism forstacking these components and for maintaining such reliable pressurecontacts may be employed.

In one embodiment, the stacking of the components of test assembly 300is similar to that described in U.S. Pat. No. 5,974,662, incorporatedherein by reference. A brief description of a representative stacking ispresented as follows.

Test assembly 300 includes the following major components for stackinginterposer 330, space transformer 340, and cable interface 120:

rear mounting plate 530 made of a rigid material such as stainlesssteel;

actuator mounting plate 538 made of a rigid material such as stainlesssteel;

front mounting plate 534 made of a rigid material such as stainlesssteel;

a plurality (two of possibly many shown, three is preferred) ofdifferential screws including outer differential screw element 536 andan inner differential screw element 539;

mounting ring 540 which is preferably made of a springly material suchas phosphor bronze and which has a pattern of springy tabs (not shown)extending therefrom;

plurality (two of many shown) of screws 542 for holding mounting ring540 to front mounting plate 534 with space transformer 340 capturedtherebetween;

optionally, spacer ring 544 disposed between mounting ring 540 and spacetransformer 340 to accommodate manufacturing tolerances; and

plurality (two of many shown) of pivot spheres 546 disposed atop (asviewed) the differential screws (e.g., atop inner differential screwelement 539).

Rear mounting plate 530 is a plate or ring (shown as a ring) disposed onthe bottom (as shown) surface of the body of cable interface 120. Aplurality (one of many shown) of holes 548 extend through the rearmounting plate 530.

Actuator mounting plate 538 is a plate or ring (shown as a ring)disposed on the bottom (as shown) surface of rear mounting plate 530.Plurality (one of many shown) of holes 550 extend through actuatormounting plate 538. In use, actuator mounting plate 538 is affixed torear mounting plate 530 in any suitable manner, such as with screws(omitted from the figure for illustrative clarity).

Front mounting plate 534 is a rigid, preferably metal ring. In use,front mounting plate 534 is affixed to rear mounting plate 530 in anysuitable manner, such as with screws (omitted from the figure forillustrative clarity) extending through corresponding holes (omittedfrom the figure for illustrative clarity) through the body of cableinterface 120, thereby capturing cable interface 120 securely betweenfront mounting plate 534 and rear mounting plate 530.

Front mounting plate 534 has a flat bottom (as viewed) surface disposedagainst the top (as viewed) surface of the body of cable interface 120.Front mounting plate 534 has a large central opening therethrough,defined by inner edge 552 thereof, which is sized to permit theplurality of conductors (e.g., contact terminals) of cable interface 120to reside within the central opening of front mounting plate 534, asshown.

As mentioned, front mounting plate 534 is a ring-like structure having aflat bottom (as viewed) surface. The top (as viewed) surface of frontmounting plate 534 is stepped, front mounting plate 534 being thicker(vertical extent, as viewed) in an outer region thereof than in an innerregion thereof. The step, or shoulder is located at the position of thedashed line (labeled 554), and is sized to permit space transformer 340to clear the outer region of the front mounting plate and rest upon theinner region of front mounting plate 534 (although, the spacetransformer actually rests upon pivot spheres 546).

Plurality (one of many shown) of holes 551 extend into the outer regionof front mounting plate 534 from the top (as viewed) surface thereof atleast partially through front mounting plate 534 (these holes are shownextending only partially through front mounting plate 534 in the figure)which receive the ends of a corresponding plurality of screws 542. Tothis end, holes 551 are threaded holes. This permits space transformer340 to be secured to the front mounting plate by mounting ring 540,hence urged against the body of cable interface 120.

A plurality (one of many shown) of holes 558 extend completely throughthe thinner, inner region of front mounting plate 534, and are alignedwith a plurality (one of many shown) of corresponding holes 560extending through the body of cable interface 120 which, in turn, arealigned with holes 548 in the rear mounting plate 530 and holes 550 inactuator mounting plate 538.

Pivot spheres 546 are loosely disposed within aligned holes 558 and 560,at the top (as viewed) end of the inner differential screw elements 539.Outer differential screw elements 536 thread into (threaded) holes 550of actuator mounting plate 538, and inner differential screw elements539 thread into a threaded bore of outer differential screw elements536. In this manner, very fine adjustments can be made in the positionsof the individual pivot spheres 546. For example, outer differentialscrew elements 536 have an external thread of 72 threads-per-inch, andinner differential screw elements 539 have an external thread of 80threads-per-inch. By advancing an outer differential screw element oneturn into actuator mounting plate 538 and by holding the correspondinginner differential screw element 539 stationary (with respect toactuator mounting plate 538), the net change in the position of thecorresponding pivot spheres 546 will be ‘plus’ 1/72 (0.0139) ‘minus’1/80 (0.0125) inches, or 0.0014 inches (0.003 cm). This permits facileand precise adjustment of the planarity of space transformer 340vis-a-vis cable interface 120. Hence, the positions of the tips (topends, as viewed) of interconnection elements 380 can be changed, withoutchanging the orientation of cable interface 120 relative to theassembly. Interposer 330 ensures that electrical connections aremaintained between space transformer 340 and cable interface 120throughout the space transformer's range of adjustment, by virtue of theresilient or compliant interconnection elements disposed on the twosurfaces of the interposer.

Conventional probe card assemblies route signals from terminals in theinner periphery of the probe card typically to terminals at an outerperiphery of the probe card by conductive traces through the probe cardsubstrate. These outer terminals are generally electrically coupled tothe test processor through conductive pogo pins extending between theprobe card and a test head. The pogo pins are then electrically coupledto coaxial cables in a cable matrix that is coupled to a test processor.In the embodiment shown in FIG. 10, the probe card and conductive pogopins are eliminated. Instead, cables 125A . . . 125N from cableinterface 120 are coupled directly via interposer 330 and to testprocessor 310. In FIG. 10, the cables (e.g., a cable matrix) may extendfrom the bottom surface (as shown) of first substrate body 225 throughopenings in rear mounting plate 530 and actuator mounting plate 538(e.g., annular openings of ring structures) to couple with testprocessor 310.

It is to be appreciated that the test assembly illustrated in FIG. 10 isone example of a suitable assembly (test assembly 300) utilizing a cableinterface. One alternative would be to couple the cable interface (e.g.,cable interface 120) directly to the space transformer (e.g., spacetransformer 340) without incorporating an interposer. FIG. 12illustrates a representative configuration.

FIG. 12 shows test assembly 1000 including test processor 310, cableinterface 120 and space transformer 1340. In this embodiment, testassembly 1000 is suitable for use in making temporary interconnectionsor contacts to a wafer such as wafer 400 having integrated devices(dies) thereon.

Referring to the components of test assembly 1000, cable interface 120includes a sufficient number of cables 125A . . . 125N (two of possiblymany shown) with conductors exposed at the surface of the interface bodyat a pitch selected, in one embodiment, to correspond with a pitch ofcorresponding contacts on space transformer 1340 (e.g., contact pointsor pads 1370).

As shown in FIG. 12, interconnection elements 1360 are mounted toconductors of cable interface 120. Interconnection elements 1360 extendupward (as viewed) from the surface of cable interface 120.Interconnection elements 1360 are, for example, resilientinterconnection elements of any of the spring shapes referenced in theaforementioned patent and application. Suitable alternativeinterconnection elements also include, but are not limited to, thoseinterconnection elements referenced above in connection with FIG. 1 andthe accompanying text.

Interconnection elements 1360 are coupled (relatively permanentlyconnected) to conductors on cable interface 120 and make temporaryelectrical connections or couplings with contact points or pads 1370 ofspace transformer 1340. Alternatively, the situation may be reversed.Interconnection elements 1360 may be coupled (relatively permanentlyconnected) to space transformer 1340 and make temporary electricalcontact (coupling) with conductors of cable interface 120.

In the illustration shown in FIG. 12, space transformer 1340 of asuitable circuitized substrate also includes a plurality of terminals1390 (two of possibly many shown) disposed on the upper (as viewed)surface thereof. In one example, the lower plurality of contact pointsor pads 1370 are disposed at the pitch of the tips of interconnectionelements 1360 (e.g., 100 mils), and the upper plurality of terminals1390 are disposed at a finer (closer) pitch (e.g., 50 mils).

Plurality of interconnection elements 1380, e.g., resilientinterconnection elements such as referenced above, are mounted toterminals 1390 of space transformer 1340 and extend upward (as viewed)from the top surface of space transformer 1340. As illustrated, in oneexample, interconnection elements 1380 are suitably arranged so thattheir distal ends are spaced at an even finer pitch (e.g., 10 mils) thantheir bases (e.g., proximal ends) to contact contact points 410 (e.g.,bond pads) on dies of wafer 400.

Unlike the test assembly shown in FIG. 10, test assembly 1000 in FIG. 12does not include an interposer. Instead, space transformer 1340 isstacked atop (as viewed) cable interface 120 within sufficient proximityso that interconnection elements 1360 make a reliable pressure contactbetween contact points or pads 1370 of space transformer 1340 andconductors of cable interface 120. Any suitable mechanism for stackingthese components and for maintaining reliable pressure contacts may beemployed.

Referring to FIG. 12, test assembly 1000 includes space transformer 1340and actuator mounting plate 1538 for stacking space transformer 1340 andcable interface 120. Rear mounting plate 1530 and actuator mountingplate 1538 are similar to similar components described above withreference to test assembly 300 in FIG. 10. In this case, rear mountingplate 1530 is a plate or ring disposed on the bottom (as shown) surfaceof the body of cable interface 120. A plurality of holes 1548 extendthrough rear mounting plate 1530. Actuator mounting plate 1538 is aplate or ring disposed on the bottom (as shown) surface of rear mountingplate 1530. A plurality of holes 1550 extend through actuator mountingplate 1538. Outer differential screw elements 1536 are threaded intoholes 1550 of actuator mounting plate 1538, and inner differential screwelements 1539 are threaded into a threaded bore of outer differentialscrew elements 1536. The differential screw elements extend throughaligned holes 1548 and 1550 and are adapted to contact pivot spheres1546 loosely disposed against space transformer 1340. The differentialscrew elements allow facile and precise adjustment of the planarity ofspace transformer 1340 vis-à-vis cable interface 120. Hence, theposition of the tip (distal end) of interconnection elements 1380 can bechanged without changing the orientation of cable interface 120 withrespect to space transformer 1340. Optional spring clips 1570 mayfurther be included between space transformer 1340 and cable interface120. Spring clips 1570, in this embodiment, permanently disposed on asurface (the bottom surface as shown) of space transformer 1340, extendsubstantially vertically to a surface (the bottom surface as shown) ofcable interface 120 to further support the orientation between spacetransformer 1340 and cable interface 120.

FIG. 13 shows another embodiment of an assembly where the cableinterface (e.g., cable interface 20) is coupled directly to the spacetransformer (e.g., space transformer 340) without incorporating aninterposer. FIG. 13 shows test assembly 1100 including test processor310, cable interface 120 and space transformer 1440.

Referring to the components of test assembly 1100, cable interface 120includes a sufficient number of cables 125A . . . 125N (two of possiblymany shown) with conductors exposed at the surface of the interface bodyat a pitch selected, in one embodiment, to correspond with a pitch ofcorresponding contacts on space transformer 1440 (e.g., contact pointsor pads 1470). Interconnection elements 1460 are mounted to conductorsof cable interface 120 and extend upward (as viewed) from the surface ofcable interface 120. Interconnection elements 1460 make temporaryelectrical connections with contact points or pads 1470 of spacetransformer 1440. Alternatively, the situation may be reversed withinterconnection elements 1460 mounted on space transformer 1440 andmaking temporary electrical connections with conductors of cableinterface 120.

Space transformer 1440 of a suitable circuitized substrate also includesa plurality of terminals 1490 (two of possibly many shown) disposed onthe upper (as viewed) surface thereof. Interconnection elements, e.g.,resilient interconnection elements, are mounted to terminals 1490 andextend upward to contact contact points 410 on dies of wafer 400.

Space transformer 1440 is stacked atop (as viewed) cable interface 120so that interconnection elements 1460 make a reliable pressure contactbetween contact points or pads 1470 of space transformer 1440 andconductors of cable interface 120. The technique of stacking, in thisexample, includes top clamp plate 1435, bottom top plate 1435, andmounting brackets 1433. Top clamp plate 1430 is, for example, an annularring or plate having an annular opening and a lip corresponding to astop edge (as viewed) of space transformer 1440. Bottom clamp plate 1435is also a ring or plate having an annular opening and a lipcorresponding to a bottom edge (as viewed) of space transformer 1440. Asshown in FIG. 13, top clamp plate 1430 and bottom clamp plate 1435 maybe brought together and fastened with, for example, screws 1432 to bindspace transformer 1440. Mounting brackets 1433 extend downward (asviewed) from bottom mounting plate 1435 to horizontally disposed (asviewed) seat portions 1437 sized to accommodate cable interface 120.

In this embodiment, cable interface 120 includes openings 1434 extendingthrough its body and aligned with openings 1431 in seat portions 1437.Differential screw elements 1436 and 1439 (similar to the differentialscrew elements described above with reference to FIG. 10 and theaccompanying text) extend through aligned openings 1431 and 1434 and areadapted to contact pivot spheres 1441 loosely disposed against spacetransformer 1440.

Another test assembly is shown in the embodiment illustrated in FIG. 14.FIG. 14 shows test assembly 600 including space transformer 640, printedcircuit board (PCB) 630, and cable interface 120. Test assembly 600 alsoincludes supply substrate 650. Supply substrate 650 is, in thisembodiment, coupled, through interconnection elements to PCB 630. Suchan assembly might be used where, for example, cable interface 120 isinsufficiently sized to accommodate sufficient conductors for couplingto an electronic component, such as wafer 400. Alternatively, suchassembly might be used where it is desired to separate signals such assupply (power) and return (ground) from high-speed data signals.

In the embodiment shown in FIG. 14, cable interface 120 includeshigh-speed data signals 125A . . . 125N and minimal (if any) power andground lines. Additional electrical connections such as power and groundare carried by supply substrate 650 that is, for example, a flexiblering substrate surrounding space transformer 640.

Supply substrate 650, in one embodiment, is a multi-layer body havingalternating layers of insulating material and conductive material. InFIG. 14, conductive layers 651 and 653 (two of possibly many shown) areshown. In this example, conductive layers carry signals such as powerand ground. In one orientation of the conductive layers in supplysubstrate 650, the conductive layers alternate between power and groundlayers, e.g., conductive layer 651 designated ground and conductivelayer 653 designated power.

FIG. 15 shows an underside view (as shown) of a portion of supplysubstrate 650, indicated in FIG. 14 by reference A-A. The surface ofsupply substrate 650 includes contact points or pads 652 and 654 andedge connectors 656. The surface of supply substrate 650 may alsoinclude, when desired, decoupling capacitors mounted to the substrate.Decoupling capacitors 659 may, for example, reduce undesired variationsin power and ground levels due to rapid impedance changes.

As illustrated, in FIG. 14, supply substrate 650 is electrically coupledto PCB 630 through interconnection elements, such as the resilientinterconnection elements noted above. Two interconnection elements arecoupled between contact points on PCB 630 and corresponding contactpoints on supply substrate 650. In one example, power and ground padsare alternated. Thus, an interconnection element is connected to groundcontact point or pad 652 of supply substrate 650 and a correspondingground contact point or pad 632 on PCB 630. Similarly, aninterconnection element electrically couples power contact point or pad654 of supply substrate 650 and power contact point or pad 634 of PCB630. It is appreciated that in other embodiments, the designation ofpower and ground contact points or pads may be reversed as necessary.

In addition to the contact points or pads (e.g., contact points or pads652 and 654), supply substrate 650 is provided with edge connectors.Referring to FIG. 14 and FIG. 15, signals such as ground and power maybe conveyed from PCB 630 to contact points or pads 652 and 654 of supplysubstrate 650, to edge connectors 656 (through respective conductivelayers 651 and 653) of space transformer 640. These ground and powersignals are conveyed from the edge of space transformer 640, throughconductive traces (e.g., conductive trace 641) in the space transformersubstrate, to contact points or pads (e.g., contact point 642) on thetop surface (as viewed) of space transformer 640. Referring to FIG. 15,in one embodiment, edge connectors 656 alternate between power andground, in one aspect, to lower the inductance of the connection. Theedge connectors are coupled to corresponding edge connectors on spacetransformer 640 through, for example, solder or pressure connections.Edge connector substrates are described in commonly-owned U.S. Pat. No.6,050,829, titled “Making Discrete Power Connections to a SpaceTransformer of a Probe Card Assembly,” incorporated herein by reference.

As illustrated in FIG. 14, signals such as power and ground are carriedto the top (as viewed) surface of space transformer 640 through supplysubstrate 650. Other connections (e.g., signal connections) may be madedirectly through the PCB in a manner similar, for example, to thatdescribed above, for example, with respect to FIG. 10 and theaccompanying text. As illustrated, interconnection elements 655electrically couple contact points on a surface of cable interface 120with contact points 633 on a lower surface (as viewed) of PCB 630.Similarly, interconnection elements 680 electrically couple contactpoints 636 on an upper surface (as viewed) of PCB 630 to contact points643 on a lower surface (as viewed) of space transformer 640.Considerations regarding pitch of the various contact points andinterconnection elements described above, for example, with reference toFIG. 10 are applicable here.

Conductors, such as copper wires or coaxial cables may be designated tocarry supply and return signals to and from the test processor or otherpower source. In this example, conductors may be coupled between PCB 630and a test processor or other power source.

FIG. 16 shows still another test assembly configuration. In thisembodiment, test assembly 700 includes space transformer 740, interposer730, and cable interface 120. Test assembly 700 also includes supplysubstrate 750 and interconnection elements such as the resilientinterconnection elements described above, to electrically couple signalssuch as power and ground between interposer 730 and supply substrate750. FIG. 16 shows interconnection elements 752 and 754 (two of possiblymany shown) for coupling power and ground between supply substrate 750and space transformer 740. The considerations above with regard to theconfiguration of supply substrate 750 with alternating conductors andinsulating layers is applicable here. Supply substrate 750 also includesa plurality of edge connectors for coupling to edges of spacetransformer 740 in a manner similar to that described above with respectto FIGS. 14 and 15 and the accompanying text, to bring, for example,power and ground to a top surface (as viewed) of space transformer 740.

As illustrated in FIG. 16, cable interface 120 is electrically coupleddirectly to space transformer 740. In this instance, interconnectionelements 680, such as the resilient interconnection elements describedabove, are coupled between contact points on an upper (as viewed)surface of cable interface 120 and a bottom (as viewed) surface of spacetransformer 740.

In the above description, examples of a cable interface are described. Ause of the cable interface is also described in testing assemblies as,for example, a replacement for conventional probe card and pogo pins. Itis appreciated that the cable interface described is suitable in otherapplications where, for example, it may be desirous to reduce theinductance effects of multi-component systems with a single interface.

In the preceding detailed description, specific embodiments of cableinterfaces and test assemblies are presented. Embodiments of techniquesfor routing signals in, for example, a cable interface or test systemare also described. It will, however, be evident that variousmodifications and changes may be made thereto without departing from thebroader spirit and scope of the invention as set forth in the claims.The specification and drawings are, accordingly, to be regarded in anillustrative rather than a restrictive sense.

1. An apparatus comprising: a cable interface comprising a plurality ofcables each comprising a conductor, each cable extending throughrespective ones of the plurality of through holes of a body of the cableinterface and having a first end terminating about a surface of thecable interface such that the conductors of respective ones of theplurality of cables are planarly aligned; an interconnection componentcomprising a component a first plurality of contact points aligned withrespective ones of the conductors of the plurality of cables and asecond plurality of contact points aligned to corresponding contactpoints of a device to be tested, wherein the interconnection componentfurther comprises a space transformer and the first plurality of contactpoints are at a first pitch and the second plurality of contact pointsare at a different second pitch; and a testing component coupled to asecond end of the respective ones of the plurality of cables, thetesting component comprising circuitry to test a device.
 2. Theapparatus of claim 1, wherein the space transformer comprises a firstinterconnection component, the apparatus further comprising a secondinterconnection component comprising a first plurality ofinterconnection elements having contact points aligned with respectiveones of the conductors of the plurality of cables and a second pluralityof interconnection elements having contact points aligned tocorresponding ones of the first contact points of the space transformer.3. An apparatus comprising: a cable interface comprising a plurality ofcables each comprising a conductor, each cable extending throughrespective ones of the plurality of through holes of a body of the cableinterface and having a first end terminating about a surface of thecable interface such that the conductors of respective ones of theplurality of cables are planarly aligned; a first interconnectioncomponent comprising a component a first plurality of contact pointsaligned with respective ones of the conductors of the plurality ofcables and a second plurality of contact points aligned to correspondingcontact points of a device to be tested; a testing component coupled toa second end of the respective ones of the plurality of cables, thetesting component comprising circuitry to test a device, wherein theconductors of the plurality of cables comprise first conductorsdesignated as data signal lines between a device to be tested and thetesting component and a second interconnection component disposed aboutthe cable interface and comprising second conductors designated asreference signal lines coupled to corresponding reference signal linesof the testing component.
 4. The apparatus of claim 3, wherein the firstinterconnection component comprises a side edge with contact pointsdisposed on a surface of the first interconnection component along theside edge coupled to respective second conductors of the secondinterconnection component.
 5. The apparatus of claim 4, wherein thesurface of the first interconnection component is a first surface, thefirst interconnection component further comprising a second surfaceopposite the first surface, wherein the first plurality of contactpoints are disposed on the first surface and the second plurality ofcontact points are disposed on the second surface.